Centrifugal pump construction



y 4, 1965 E. M. POOLE 3,181,471

CENTRIFUGAL PUMP CONSTRUCTION Filed June 23, 1961 2 Sheets-Sheet 1 INVEN T OR.

0 yEdward M. Pool 2 ATTORNEY May 4, 1965 E. M. POOLE ,4

GENTRIFUGAL PUMP CONSTRUCTION Filed June 23, 1961 2 Sheets-Sheet 2 FIG.2

INVENTOR.

BY Edward M. Poole ATTORNEY United States Patent 3,181,471 CENTRIFUGALPUMP CONTRUCTI8N Edward M. Poole, Alliance, Ohio, assignor to TheBabco'clr & Wilcox Company, New York, N312, a corporation of New JerseyFiled June 23, 1961, er. No. 115M339 2 Qlaims. (Cl. 103-103) Thisinvention relates in general to a centrifugal pump used for thetransportation of fluids and in particular to a new and improved type ofimpeller for use therein.

Centrifugal pumps are widely used in the transportation and/orpressurization of liquids and normally consist of a casing having inletand outlet openings and having an impeller rotatively mounted therein.Such an impeller is generally a flat circular plate, on at least oneface of which are disposed a plurality of vanes. These vanes usuallyextend outwardly from a center inlet channel in the impeller to itsperiphery to form flow channels through which the pumped fluid flows.Inasmuch as the vanes forming the channels are generally of a uniformcross section from the central inlet channel, or eye as it is sometimesreferred to, to the outer periphery, the channels themselves aregenerally wedge shaped, expanding rom a relatively narrow width at theeye to a relatively large width at the outer periphery.

These pumps have been found satisfactory for the transportation ofsingle phase fluids, but when fluidized gassolids mixtures are pumped ithas frequently been found that the solids portion tends to separate outon the back side of the impeller vanes and eventually plugs the pump.Multi-phase transfer systems may be found in the chemical industry wheresuspensions of very finely divided solid catalysts are fluidized ingaseous suspensions. Often, due to the segregation described above, suchsuspensions are separated into light and heavy components, aretransported separately, and then subsequently recombined. Unfortunately, it is not possible to establish and maintain a continuous flow ofa finely divided solid in a suspension gas in a closed circuit with thistype of transport.

The present invention is based on the discovery that in a centrifugalpump this separation or segregation is caused by the wedge shapedchannels formed on the impeller wheel by the outwardly extending,uniform Width vanes, which permit recirculation within the channels ofthe fluid being pumped as it passes from the center inlet of the pump tothe peripheral discharge. It was found that the separation of theentrained solids from the entraining gas during flow of material iseffectively prevented when the impeller is provided with a plurality ofgrooves in one face rather than a plurality of vanes.

Accordingly, the present invention provides a centrifugal pump having asubstantially circular casing with a central fluid inlet at one sidethereof, a fluid outlet at a point on the periphery, and an impellermeans comprising a circular disc member rotatably mounted in the casinghaving a circular channel communicating with the fluid inlet and aseries of angularly spaced grooves formed in one face of the disc memberand extending from the circular channel to periphery of the disc memberwhich communicate with the fluid outlet.

Further, the present invention provides an impeller in which the aboverecited grooves have a substantially uniform, narrow cross sectionextending from the circular channel to the outer periphery of the discmember.

Additionally, the present invention provides a centrifugal pump whereinthe impeller means is rotatably mounted in a horizontal position withinthe pump casing with the central fluid inlet providing a downward flowinto the central circular channel of the impeller means.

The various features of novelty which characterize my ddhlfill lPatentedMay 4, l dd invention are pointed out with particularity in the claimsannexed to and forming a part of this specification. For a betterunderstanding of the invention, its operating advantages and specificobjects attained by its use, reference should be had to the accompanyingdrawings and descriptive matter in which Ihave illustrated and describedpreferred embodiments of the invention.

Of the drawings:

FIG. 1 shows a cross section of the pump of the present invention takenalong the centerline of the impeller shaft; and

FlG. 2 is a plan view of a portion of the impeller taken along line 2-2of FIG. 1.

The centrifugal pump of the present invention is shown in FIG. 1 andconsists of a generally circular casing having a central fluid inlet 14disposed in one side thereof and a peripheral fluid outlet 16. Thiscasing is comprised of an upper and a lower, generally flat, matingcircular plates is and adapted to be secured at their peripheries, as bybolts 22, to form a central cavity 24. A gasket may be provided at thebolted joint to make the casing tight. The fluid inlet 14 is coaxialwith the cavity 24 and extends through the upper plate 18 into thecavity. The lower plate 20 has a shaft opening 26 extending therethroughcoaxial with the inlet 14 and the cavity 24. Extending outwardly fromthe lower plate 29 and coaxial with the shaft opening 26 is a shaftbearing housing 28, of a type well known in the art, in which a shaft Siis rotatabiy mounted. This shaft extends from the outer end of thebearing housing 28 into the cavity 24 of the casing and is provided witha means for receiving motive power, such as pulley 32, at its outer end.A fluid impeller means comprising a circular disc 34, is mounted on theend of the shaft 30 within the cavity 24 so as to be rotatably movabletherein by the rotation of the shaft and thus to pump a fluid from theinlet 14 to the outlet 16. As may be seen in FIG. 2, the cavity 24 ispreferably of volute shape, although its contour may be of the diffusertype (not shown). Both types are well known in the pump art. With thevolute, the fluid outlet 16 is located in the portion of the volutehaving the largest cross section;

The circular disc impeller 34 is provided with a central circular inletchannel 36 on the side adjacent the fluid inlet 14 so that the inletchannel is in communication therewith to receive the incoming fiuid thatis to be pumped. Extending outwardly from the inlet channel, and on thesame face of the impeller disc, there is a pl-urality of angul-arlyspaced grooves 38 which extend to the outer periphery of the impellerdisc so they are in communication with the fluid outlet 16. The impellerdisc may also be provided with central conical portion 4t) which extendsinto the central fluids inlet 14 so as to provide an annular flow path42 of substantially constant cross section from the inlet to thecircular inlet channel As seen in FIG. 2, the grooves 38 in the @face ofthe impeller disc 34 are backward pitched as they extend from the centerof the disc to the outer periphery, i.e. are inclined in a directionopposite to the rotation of the disc, which rotation is indicated byarrow 44. However, radial grooves may also be used. In either case, thegrooves in the impeller disc are characterized by the fact that they arerelatively narrow in cross section and have a substantially uni-formcross section from the inlet chan nel to the periphery of the disc.

With this impeller construction having a series of narrow angurlarlyspaced grooves of substantially uniform cross section throughout theirlength, it has been possible to pump a homogeneous gas-solids suspensioncontinuous- 1y for extended periods without phase separation within Ain...

particles finally plugging the entire .a mixture density of 6 pounds percubic foot.

diameters with varying numbers of grooves.

transverse to the flow: proceeding from the center to the V periphery ofthe impeller, so that the more dense solids traction separates from thelighter gaseous traction and obstructs the flow passage, theaccumulation of solids pump inoperable. I r A'specific example of thepump of the present invention is one which has an impeller disc with anoutside diameter or 16% inches and 32 grooves each having /1 x A" crosssectional flow areas extending from the central inlet channel to theimpeller periphery. When this impeller is driven at a speed of 3600 rpm.the pump has a capacity of 8 cubic feet per minute and develops a 6p.s.-i. differential head. For this performance the average particlesize of the fluidized solids, which in this case ,was graphite, rangedfrom 0.05 micron to 20 microns, and'with the carrier gas, carbondioxide, produced After a three week run an inspection of the impellerdisc, upon disas'sembly, disclosed no trace of phase separation or n eIt has also been found that in pumping a gas-solids suspension it isadvantageous to arrange the pump with the particular embodiment of thepresent invention, different capacity pumps could require impeller discsof other while the grooves also may have dimensions different than thosegiven above, the use of narrow'groovesof substantially uniform crosssection will produce the results here'- indescribed. v

While in accordance with the provisions of the statutes I haveillustrated and described herein the best form and mode of operation ofthe invention'now known to me,

those skilled in the art will understand that changes" may' be madeinthe form of the apparatus disclosed-without passage rendering theMoreover,

departing from the spirit of the invention covered by my a pensionhaving a substantiallycircular ,casing with a centrally disposedgas-solids suspension inlet arranged in one side thereof and aperipherally disposed gas-solids suspension outlet, a fluid impellermeans comprising a 4 generally flat imperforate circular disc memberrotatably mounted in said casing and having a flat face thereofsubstantially in contact withone side of said casing, said disc-memberhaving a centrally disposed annular inlet channel formed in said flatface thereof communicating with said fluid inlet, a multiplicity ofangul'arly spaced substantially straightopen grooves formed in said flatface of said disc member and extending from said annular inlet channelto the periphery ofsaid disc member and communicating with said casingperipheral outlet, said grooves having a substantially constant narrowwidth from said inlet channel to the outer periphery of said disc memberconstructed to minimize separation of the solids from the gas. a t V 2.A centrifugal pump for pumping .a gas-solids suspension having asubstantially circular casing with a censan iauy in contact with oneside of said'casing, said 5 disc member having a centrally disposedannular inlet channel formed in said flat face thereof communicatingwith said fluid inlet, a multiplicity of angul-arly spaced substantiallystraight open grooves [formed in said flat face of said disc member andextending from said annular inlet channel to the periphery of said discmember and communicating with said casing peripheral outlet, saidgrooves having a substantially constant narrow width from said inletchannel to the outer periphery of said disc member, said impeller meanshaving a central conical portion extending into said inlet andcooperating therewith to form an annular feed passage to said inletchannel so as to form a continuous narrow flow pathrfor Nicholas er al.ids- 450,491 4/91 557,300 3/96 Barber 103-115 885,108 4/08 Trent 103-1151,003,020 9/11 Webb 103-115" 1,289,337 12/18 Wilfley 103-115 1,586,1605/26 Mauron et al. 103-115 1,986,836 1/35 MacNeille 103-115 1,988,8751/35 Saborio 103-115 2,013,455 9/35 Baxter 103-115 2,046,226 6/36Weightman et al. 103-115 2,165,808 7/39 Murphy 103-115 2,255,287 9/41Jacobsen' 103-103 2,438,442 3/48 Holt 103-115 2,636,442 4/53 Roth103-115 V FOREIGN PATENTS 512,412 7/52 Belgium.

7,598 10/04 GreatBritain.

JOVWSEPH n. BRANSVON, IR., Primary Examiner, LAURENCE v. EFVNER,Examiner.

1. A CENTRIFUGAL PUMP FOR PUMPING A GAS-SOLIDS SUSPENSION HAVING ASUBSTANTIALLY CIRCULAR CASING WITH A CENTRALLY DISPOSED GAS-SOLIDSSUSPENSION INLET ARRANGED IN ONE SIDE THEREOF AND A PERIPHERALLYDISPOSED GAS-SOLIDS SUSPENSION OUTLET, A FLUID IMPELLER MEANS COMPRISINGA GENERALLY FLAT IMPERFORATE CIRCULAR DISC MEMBER ROTATABLY MOUNTED INSAID CASING AND HAVING A FLAT FACE THEREOF SUBSTANTIALLY IN CONTACT WITHONE SIDE OF SAID CASING, SAID DISC MEMBER HAVING A CENTRALLY DISPOSEDANNULAR INLET CHANNEL FORMED IN SAID FLAT FACE THEREOF COMMUNICATINGWITH SAID FLUID INLET, A MULTIPLICITY OF ANGULARLY SPACED SUBSTANTIALLYSTRAIGHT OPEN GROOVES FORMED IN SAID FLAT FACE OF SAID DISC MEMBER ANDEXTENDING FROM SAID ANNULAR INLET CHANNEL TO THE PERIPHERY OF SAID DISCMEMBER AND COMMUNICATING WITH SAID CASING PERIPHERAL OUTLET, SAIDGROOVES HAVING A SUBSTANTIALLY CONSTANT NARROW WIDTH FROM SAID INLETCHANNEL TO THE OUTER PERIPHERY OF SAID DISC MEMBER CONSTRUCTED TOMINIMIZE SEPARATION OF THE SOLIDS FROM THE GAS.